The field of the invention is disconnect switches, and more particularly, manually operated disconnect switches having a set of movable contacts which are pivoted between an opened and closed position by rotating a crossbar.
In relatively small disconnect switches such as that disclosed in U.S. Pat. No. 3,958,095, a molded crossbar is mounted to a base for rotation about a horizontal axis and it carries a set of three movable contacts between an opened and closed position. The disconnect switch is typically mounted within a cabinet and is operated manually by a handle which is coupled to the crossbar by a trip mechanism such as that disclosed in U.S. Pat. No. 3,959,615. A disconnect switch made according to the teachings of the above patent offers numerous advantages over prior disconnect switches, including ease of assembly and maintenance, versatility and reliability.
Economic considerations become very important when these same advantages are to be achieved in larger disconnect switches. The larger current carrying capacity requires proportionally larger contacts, greater spacing between them and greater contact pressure. The net result is a need for a much larger and stronger supporting structure, contact structure and crossbar assembly. Cost factors preclude scaling up successful designs such as that disclosed in the above-cited patent, and new designs must, therefore, be created to achieve the same results in larger disconnect switches.